poj 2386(深搜或广搜)

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Lake Counting
Time Limit: 1000MS Memory Limit: 65536KTotal Submissions: 17917 Accepted: 9069

Description

Due to recent rains, water has pooled in various places in Farmer John's field, which is represented by a rectangle of N x M (1 <= N <= 100; 1 <= M <= 100) squares. Each square contains either water ('W') or dry land ('.'). Farmer John would like to figure out how many ponds have formed in his field. A pond is a connected set of squares with water in them, where a square is considered adjacent to all eight of its neighbors. 

Given a diagram of Farmer John's field, determine how many ponds he has.

Input

* Line 1: Two space-separated integers: N and M 

* Lines 2..N+1: M characters per line representing one row of Farmer John's field. Each character is either 'W' or '.'. The characters do not have spaces between them.

Output

* Line 1: The number of ponds in Farmer John's field.

Sample Input

10 12W........WW..WWW.....WWW....WW...WW..........WW..........W....W......W...W.W.....WW.W.W.W.....W..W.W......W...W.......W.

Sample Output

3

这道题目比较基础,可以深搜也可以广搜

深搜快一点 36ms,广搜47ms。很好的练习题目。

把注释的去掉就是深搜了。

#include <stdio.h>#include <queue>using namespace std;#define N 102char map[N][N];int n,m;struct Node{    int x,y;};int dis[10][3]={ {0,1},{0,-1},{-1,0},{1,0},{-1,-1},{-1,1},{1,-1},{1,1} };void search(int a,int b){    /*map[a][b]='.';    for(int i=0;i<8;i++)    {        int tmpx=a+dis[i][0];        int tmpy=b+dis[i][1];        if(tmpx>0 && tmpx<=n && tmpy>0 && tmpy<=m && map[tmpx][tmpy]=='W' ){            //map[tmpx][tmpy]='.';            search(tmpx,tmpy);        }    }*/    Node tmp,be;    be.x=a,be.y=b;    queue<Node> v;    v.push(be);    map[a][b]='.';    while(!v.empty())    {        be=v.front();        v.pop();        for(int i=0;i<8;i++)        {            tmp.x=be.x+dis[i][0];            tmp.y=be.y+dis[i][1];            if(tmp.x>0 && tmp.x<=n && tmp.y>0 && tmp.y<=m && map[tmp.x][tmp.y]=='W' )            {                v.push(tmp);                map[tmp.x][tmp.y]='.';            }        }    }}int main(){    int i,j,count;    while(~scanf("%d %d",&n,&m))    {        getchar();        count=0;        for(i=1;i<=n;i++){            for(j=1;j<=m;j++){                scanf("%c",&map[i][j]);}  ///缺了括号,害死人啊            getchar();}        for(i=1;i<=n;i++)            for(j=1;j<=m;j++)                if(map[i][j]=='W')                {                    //printf("%d %d\n",i,j);                    search(i,j);count++;                }        printf("%d\n",count);    }    return 0;}
深搜递归写法
#include <stdio.h>#include <queue>using namespace std;#define N 102char map[N][N];int n,m;void search(int i,int j){    if(map[i][j-1]=='W') { map[i][j-1]='.'; search(i,j-1); }    if(map[i][j+1]=='W') { map[i][j+1]='.'; search(i,j+1); }    if(map[i-1][j]=='W') { map[i-1][j]='.'; search(i-1,j); }    if(map[i+1][j]=='W') { map[i+1][j]='.'; search(i+1,j); }    if(map[i-1][j-1]=='W') { map[i-1][j-1]='.'; search(i-1,j-1); }    if(map[i-1][j+1]=='W') { map[i-1][j+1]='.'; search(i-1,j+1); }    if(map[i+1][j-1]=='W') { map[i+1][j-1]='.'; search(i+1,j-1); }    if(map[i+1][j+1]=='W') { map[i+1][j+1]='.'; search(i+1,j+1); }}int main(){    int i,j,count;    while(~scanf("%d %d",&n,&m))    {        getchar();        count=0;        for(i=1;i<=n;i++){            for(j=1;j<=m;j++){                scanf("%c",&map[i][j]);}  ///缺了括号,害死人啊            getchar();}        for(i=1;i<=n;i++)            for(j=1;j<=m;j++)                if(map[i][j]=='W')                {                    //printf("%d %d\n",i,j);                    search(i,j);count++;                }        printf("%d\n",count);    }    return 0;}




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